Device for protecting buildings against earthquakes.



L. KDHL.

DEVICE FOR PROTECTING BUILDINGS AGAINST EARTHQUAKES.

APPLICATION FILED JULY 3.19l4.

Wfl-Messrs:

COLUMN/ PLANOORAPII C0.. WASHINGTON. D. C.

LUDWIG KOHL, OF FRANKFORT-ON-THE-MAIN, GERMANY.

DEVICE FOR PROTECTING BUILDINGS AGAINST EARTHQUAKES.

Application filed July 3, 1914.

To all 1li/1,0m t may concern Be it known that I, LUDwio Kenn, a subject of the German Emperor, and resident of Frankfort-on-the-Main, Germany, have invented certain new and useiiul Improvements in Devices for Protecting Buildings Against Earthquakes, ot' which the following is a specification.

The hitherto known devices for protecting buildings against earthquakes, consisting of ball-bearings between basement and building, have so serious drawbacks that their practical employment is impossible, because: l, the connection between buildingl and basement was unsatisfactory; 2, they do not decrease the vehemency of the horizontal shocks to the minimum extent required; 3, they do not allow an eXact static calculation of the building previously and independently from the strength of the shocks; and l, they do not take up the verticalshocks.

rlhe present invention proposes to overcome all these drawbacks detrimental to the security of the Ibuildings in earthquake regions, by allowing to effectively protect the buildings against horizontal and vertical shocks within wide limits.

The accompanying drawing illustrates how the invention is put into practice.

Figure 1 is a Vertical section through the ball-bearing, Fig. 2 shows the vertical anchorage.

The main principle of the invention is as follows :-Between foundation or basement and the building proper, an appropriate ball-bearing is inserted, whereby the building can move within the required limits as resistanceless as possible toward the basement, without compensating thereby the necessary connection in vertical direction between basement and building. For this purpose, in the gap between building and basement, the two ball-bearings (L are arranged, the upper one being connected with the building and the lower one with the basement. The bearings a are turnable for small degree by means of strong screwbolts movably arranged in the basement and building respectively, so that the bearings are allowed to tilt somewhat toward the horizontal plane or to return from the tilted position into the horizontal position. Both movements are essential, particularly the latter one. For, in order to obtain a smallest possible resistance against a move- Specification of Letters Patent.

Patented Nov. 2, 1915.

Serial No. 848,989.

ment of the building toward the basement in horizontal direction, it is essential that the bearing planes of all balls lie practically in the same horizontal plane. The screw-bolts Z serve thus ehieliy for making all ball-bearing planes, as :tar as possible, parallel to one another. This exact parallel position is an essential requirement for the proper working or operation oi the device, because with non-lnirallel bearing-planes the balls, with large movements of the basement, would roll out between the bearingplanes, which is impossible with parallel bearing planes.

The material ot' the ball-bearings a is steel ,or the like hard metal, whereby the balls, which are under high pressure between the bearing planes, are prevented from beingl impressed in the latter whereby they could not more in lateral directions. The bearing planes oit' the ball-bearings a, are perfectly smooth and lubricated, for attaining a smallest possible resistance against lateral movements of the balls. This minimum of resistance must be attained, because this resisting power is the impact. which acts as horizontal power on the building and which forms the outer load oi' 'the building by action of horizontal earthquake shocks, from which load the static calculations must be started. The smaller the resisting power, the lesser is also the strain on the building. Besides, the essential advantz'ige `i'or solving the question ot' earthquakes results therefrom that the impact acting ou the building becomes in wide limits independent from the strength and extent of the earthquake shocks; the impact becoming exclusively a function of the pressure (G) on the ball, that is :0d-G, 0 boing` the friction coellicient of the rolling ball. lVith well-lubricated smooth ball-bearings and. 'for large loads, generally present in the art ot' building, 020.002, so that generally the impact=0-002 G, that is proportionate to the pressure of the ballbearing.

Between the two ball-bearings. the abovementioned balls rf are located, which are also made ot' hard material. Each ball is surrounded by a separate cage or ring nl, which has the purpose to prevent the ball` upon a non-parallel position oi the two l'iall-bearings happening eventually, from rolling out ot' its seat between the bearing planes, without a perceptible resistance being opposed to lateral movements of the basement. For

this purpose, the ring runs on separate small balls e and is thus movable in all directions, whileseparate springs f, which are in balance in the initial position, that is before the horizontal stroke, prevent the ring (Z itself from rolling out between the ballbearings ce. For reducing friction between the balls c and ring (Z, small antifriction rollers are inserted between ring CZ and ball c.'

kThe operation of this safety-device or cage is simple: Byrthe action of horizontal earthquake shocks, the basement moves suddenly sideward, while the building remains practically7 at standstill owing to its power of inertia, the friction powers in the ballbearings. producing a small displacementY ofV the building only in the direction of the movement of the basement. VrThis lateral displacement will be the lesser, the smaller are the friction powers. it the same time, the latter act as impactson the building. rlfhesev impacts represent theouter load of the building by action of horizontal earthouake shocks. lt is mentioned above that the Vimpacts within wide limits attain the amount of 0.002 G (Gzball pressure) with v-.Yell-lubr'icated ball-bearings.V The same movement is repeated for the following sudden Vmovements of the basement, alternately in one and the other direction, until finally after gradual decrease of the movement of the ground the standstill is again attained. ln the position of rest, each ball must, unless a permanent displacement of the basement has happened, again assume its initial position. rhe ring Zdoes Vnot-act, as long as `the ball-bearings@ are or remain parallel, it'being only moved, each time for half of the movement of the basement, alternately out of and into its initial position owing to the; lateral movement ofthe ball c by action of a horizontal earthquake. Its vfunctionproper begins, however, as soon as the balldoes not more receive a vertical pressure owing to the non-parallel position of the two ball-bearings a, whereupon'the Vring arrests the ball in its seat so that it cannot roll out between the ball-bearing planes. l

rlhe vertical anchorage consists of a slide al, which runs on small rollers 1 or the like,

av spring c1 attachedto the slideV and made fast in the basement, and the anchor proper d1. The latter is pivotally connectedy at the top and bottom endwith the building yand slide respectively in such a way that it can tilt inall directions of the horizontal plane.

The slide al runs compulsorily in a corresponding .cavity of the basement, the spring c1 controlling the position of the slide.

Upon the basement being pushed'aside by action of horizontal earthquake shocks, the slide moves upward and thespring V01 1s tensioned, owing to the Vupper buildingre- Y maining in its position. Thereby, a horizontal Vpower is produced in the anchor d1,

which serves to return the upper building j v.again to its initial position with reference to the basement, as soon, as a permanent displacement of the basement has happened. At the same time, this horizontal power limits the movement of the 'upper building in lateral directiomas soon as for any reason the upper building would tend to run off from its basement. c

VThe main advantages of the safety-device arcvthat horizontal and vertical shocksV are effectively neutralized, and that the horizontal shocks are reduced Vto the minimum to be attained at all in the art yof building, so that the buildings are protected, as lfar-v as possible, against the devastating effects ofearthchorage between basement and building proper, the combination of a freely movable, automatically adjustable ball cage-consisting of a ring, race-balls springs to secure the ring in positiom-a for the ring, andl ball located in said cage, an upper andv a e lower ball-bearing plane to inclose said ball, screw-bolts to adjust said ball-bearing planes, aV vertically movable, spring-controlled slide in the basement, and an anchor to pivotally intervene between said slide and the building proper Vand adapted to move in anyV direction ofthe horizontal plane, substantially as and for thekpurpose set forth. l

e LUDWG VKOHL. Witnesses s CARL BUCHMLLER, JEAN GRUND.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner ofPatents, i Washington, D. C. 

